Posts Tagged ‘earthbags’

Alternate title: How to Build an Earthbag House That Will Last as Long as the Pyramids. I can’t say for sure that the pyramids were built this way, but this video describes a reasonable theory of how the blocks of the pyramids were made with natural materials from the Giza Plateau – limestone, kaolin clay, sodium carbonate, lime and water. According to the video, the mixture consists of 95% limestone aggregates, 5% rock making binder and between 12%-17% water. The same methods could be used to create rock hard earthbags with incredible durability. And it’s simple enough that anyone can do it. It’s ancient technology after all.

There’s a great deal of very interesting information about this by Professor Joseph Davidovits and other researchers at the Geopolymer Institute. Here are a few quotes from their Archeology page.
“The pyramids stones are man-made (synthetic, artificial), cast in situ.”
“The Great Pyramid of Kheops is comprised of about 2.5 million blocks, most weigh two tons and could have been hauled by no less than sixty men. But some weigh up to seventy tons and these are to be found, not at the base of the pyramid, but some forty meters high. Since the ancient Egyptians did not yet have the wheel, they would have needed more than two thousand men to haul each block.”
“How could the Ancient Egyptians have cut these stones, which are extremely hard, with only the most primitive of tools? At best they would have been able to use copper saws, and copper is a softish metal, incapable of hewing the hard limestone blocks from which the early pyramids are constructed.”
“If the stones were carved, as most people believe, where are the fragments of broken stone left over? Limestone frequently splits on being cut. 5 million tons of limestone blocks must have produced millions of broken blocks and fragments. Yet, not a trace of them has ever been found.”
“The pyramid casing stones are light in density and contain numerous trapped air bubbles, unlike the quarry samples which are uniformly dense. If the casing stones were natural limestone, quarries different from those traditionally associated with the pyramid sites must be found, but where?”
“In natural stones, we expect to find elements that had the time to crystallize. However, silicates in pyramids stones are completely amorphous (not crystallized). This allows us to think that we are in presence of a cementitious process. The silicates were formed in a very short period of time.”
“This photo shows a sample of the casing from the ascending passage of Kheops great pyramid… the cross section is characterised by the presence of organic fibers and air bubbles that do not exist in normal situation, especially in a 60 millions years old limestone from the eocene era!”
“Barsoum’s team took a fresh look at 15 samples using scanning- and transmission-electron microscopes. The samples contain ratios of elements, such as calcium and magnesium that do not exist in nearby limestone. The imaging also revealed regions of amorphous structure. Both observations suggest that other substances were added to make a concrete mix.”
“The famous Massachusetts Institute of Technology, Boston, USA, is supporting Prof. Davidovits’ re-agglomerated stone (concrete) pyramid theory. At MIT, Professor Hobbs and two colleagues and students are experimenting the construction of a small scale pyramid using the method recommended by Davidovits.”

This video helps explain the geopolymer process. In this video Professor Davidovits explains how they made a man-made sample of re-agglomerated stone and then submitted it for laboratory analysis. The laboratory said it was natural stone. For more details, go to the Geopolymer Institute YouTube channel http://www.youtube.com/user/kadamix to see more videos such as: Bricks made at low temperature, low energy, low cost http://www.youtube.com/watch?v=zjeVeDVtghc&feature=related,

If the microscopic, x-ray and nuclear magnetic resonance spectroscopy analysis doesn’t convince you, think about the Colosses of Memnon, which these same geopolymer scientists believe were cast of amalgamated/agglomerated stone in a similar manner as the pyramids using geosynthesis (limestone treated like a concrete).
“In antiquity, the statues commanded respect; the Colosses of Memnon are monoliths: they are made from a single block of stone weighing nearly 1000 tonnes and standing on a pedestal of 550 tonnes. They are 20 metres high, equal to a seven storey building. The stone from which they are made is quartzite, which is practically impossible to carve.”
“None of the great quartzite blocks bear any trace of tools that is so common in the sandstone and granite quarries: a material that is so hard, so refractory in the face of sharp tools cannot, it is true, be worked by the same methods as ordinary sandstone nor even of granite. We know nothing of how the blocks of such a rock were squared, how their surfaces were dressed or how they were given the beautiful polish that can still be seen in some places… Did the sculptor, in the middle of engraving a hieroglyphic character, strike one of the flints or pieces of agate that are encrusted in the material, the line of the character continued in all its purity, and neither the agate nor its enveloping stone bear the slightest crack.”

Summary: Whether or not the pyramids were made with geopolymer cast stones could be debated endlessly. However, the key point for natural builders is geopolymer scientists have developed recipes using natural materials and simple production techniques that can be utilized in rammed earth and earthbag construction. This is an exciting new field of opportunity in my opinion. Please refer to the publications by Professor Joseph Davidovits and other researchers at the Geopolymer Institute for complete information.

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Laying a course of mesh earthbags to test their working properties.

Laying a course of mesh earthbags to test their working properties.

I finally had a chance to build with mesh bags. Previously I had made some test bags, but this week we included a whole course of mesh bags in our current Cool Pantry project. More photos coming soon.

In this post I want to describe some of the differences in working properties between mesh and poly bags. Bag properties will vary between suppliers, so your experience may be different, but with our bags the results so far are very positive in favor of mesh bags in most every way.
– 1/4 the cost of poly bags in our area! (6.5 cents versus 27 cents.) This savings would be substantial on a full sized home. The cost difference is largely due to buying recycled bags at the farmer’s market. We’re using a product that’s in perfect condition, but would likely be thrown away. Poly bags have more uses and fetch higher prices even when recycled.
– Can add an additional 1-2 extra buckets per bag (6-7 versus 5). This creates longer bags with more overlap, which creates stronger walls.
– Can tie the tops of bags with one 4” piece of galvanized wire. I twist the bag closed, insert one end through the mesh, bend the wire over and poke the other end into the contents. This means you can use half the wire and close the bag in about one third the time of our typical method. (Small improvements like this add up over time.)
– Faster plastering due to better bond. (We’ve yet to verify this, but this is what I expect.) A previous post discussed improved bonding strength, but plaster work should go faster as well.
– We pounded the mesh bags very hard because the bond beam sits on this course, and yet there was no damage to the mesh.
– There was extensive drying in just a few hours.

Other comments:
– A slightly moister mix will reduce spillage through the mesh. Only 2-3 teaspoons of fine material fall out with this method.
– Requires a smaller bucket chute. We’re using a 3 gallon (11.4 liter) stainless steel bucket with the bottom and handle cut off. It’s 9” high and tapers from 11” wide at the top to 8”.
– A plastic bucket of similar size broke almost immediately. (Anyone else getting fed up with crap tools?) Might as well pay a little extra and have something that will last for years.
– Mesh bags are stretchier and take a second or two longer to insert the bucket chute.
– Mesh can tear if hit hard with the corner of a tamper. Round the edges of your tampers and hit the bags flat. (None of our bags tore, but this is something to watch out for.)
– Someone could experiment with double bags for seismic areas and report back their results.

Refer to our previous blog posts for more info:
Hyperadobe Update from Brazil
Open Weave Fabric: Ideal Working Properties
Hyperadobe Continued

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What’s the most efficient, cost-effective way to build with earthbags? How can you enclose the most space with the least time, effort and money? Well, it depends in part on climate, individual skills and preferences as far as styles/building types. (Other factors will be covered in a future post.)

In general, round shapes are the most efficient. They create the most amount of floor space for a given wall length. This is easily demonstrated by drawing a circle and a square using the same lineal distance of walls. For example, draw an 18’ diameter circle, which will have an area of 254 square feet and circumference of about 56.5’. Divide 56.5 by 4 (= 14.1’) to obtain a square with the same total wall length. A square with 14.1’ per side has an area of about 200 square feet. So in this example there’s a gain of 54 square feet of floor space. (Draw this with your kids. It’s a great learning experience.)

So why do builders churn out square/rectilinear structures? Because modern building materials are rectilinear – plywood, OSB, sheetrock, etc. But we know these materials are energy intensive, costly, lead to monotonous designs and have negative impacts on the environment. Earthbag building frees us from these constraints and enables the use of more efficient round shapes. In addition, round shapes are inherently more stable. “Round is sound” as they say.

Size is also important. Large houses require much more time, labor, skill and materials and can easily wear you down, even more so for owner-builders. It’s far better to build only what you need. You can always add on later. Build with cash one stage at a time.

Another factor to consider is fill material – what goes in the bags. Lightweight materials such as scoria are much faster and easier to use than soil. This one factor alone can cut the labor by severalfold, because scoria is lightweight, easy to work with and requires less tamping. Scoria is insulating and so it’s ideal for extreme climates. Plus, scoria doesn’t rot, burn, attract pests, etc. One limiting factor is it’s less stable in certain applications such as straight walls and tops of domes that curve in too quickly.

And the winner is? I’ll give it a tie between roundhouses and domes, depending on the variables listed above. Small to medium sized roundhouses with simple roof designs have an edge in many cases, especially rainy climates and for those with carpentry skills. In dry climates, domes may be more efficient. Organic shapes that approximate circles are a close runner-up, although this often complicates roof construction.

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Do earthbags really become hard as rock or is this exaggeration? I did a little experiment on the roundhouse we’re currently building to find out.

The answer depends primarily on the choice of fill material and the degree of compaction. The moisture content and curing process also play a role. We used road base – the material used under roads in many parts of the world – moistened slightly and tamped solid. The video shows the result after about one or two weeks of drying.

Note the ringing ‘ching-ching’ sound when I tap the earthbags with a putty knife. It almost sounds like I’m hitting stone. I tap a compressed earth block (CEB) for comparison. CEBs contain about 6% cement and are rammed in a press at high pressure, so you expect them to be harder. But in reality they’re fairly similar as you can hear for yourself. In both examples, densely compacting correct soil mixtures create very strong building materials. They begin to approach the strength of stone at a fraction of the cost and labor.

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Almost every part of a new home can be obtained at lower cost through using recycled goods and bartering. The concept is very simple. Someone, somewhere likely has an excess of what you’re looking for and will gladly trade or sell those goods at below market cost.

For instance, plumbers replace sinks and bathtubs routinely. Busy plumbers have so many old ones that they can barely give them away fast enough. While some fixtures will be in poor condition, many are replaced because they have a small chip or because people want something new and more fashionable.

You can buy recycled building materials from Salvation Army or Habitat Restores and similar thrift stores. This makes shopping convenient because there’s a large selection under one roof.

Often the lowest prices can be found by dealing directly with people who have items they no longer need. It’s amazing what can be scrounged from remodelers, dumpsters, trash haulers, demolition companies and curb sides (drive around at night in affluent neighborhoods). Workers at city dumps typically sort out items of value and sell at very low cost. And don’t forget about yard sales and Craigs List.

You can use the same process to find low cost earthbags (sandbags). Network with farmers and feed stores in your area to locate used grain or feed bags in good condition. Make sure they are comparable in strength to new sandbags and have been stored away from sunlight. You could buy one new sandbag for comparison, and fill and tamp one sample bag before buying a large quantity.

I know artists who have built their homes with recycled materials, and the end results are stunning. One of these artists mixed various colored 4”x4” tiles using leftovers from tile workers and made the most beautiful countertop I’ve ever seen.

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There’s great, untapped potential for superinsulated earthbag buildings in cold climates. Here’s a way to combine the best features of earthbags and yurts. The basic idea is to combine earthbag walls filled with lightweight insulation such as scoria (lava rock), with a traditional yurt roof frame that’s insulated with perlite or vermiculite.

Yurts (ghers) have been used in Mongolia and other areas for centuries. Traditional yurts are well suited for cold, windy places, in part because the wind just blows around them. They can, however, be made even more comfortable with extra insulation in earthbags.

Scoria is perfect for superinsulated earthbag walls: low cost, all natural, rot proof, fireproof, doesn’t attract pests, lightweight and easy to work with. Scoria is great for building walls since the aggregates tend to lock together and form stable walls. Tie courses together with twine for best results, and then cover walls with canvas.

Yurt roof frames are readily available through numerous suppliers, and fast and easy to assemble. The steel tension cable is strong yet light. They are very resource efficient, using minimal wood, but often lack adequate insulation. I recommend tying bags of lightweight insulation to the bottom of the frame. Perlite and vermiculite would be excellent choices for ceiling insulation since they’re very lightweight.

This design is portable, just like traditional yurts. The entire structure can be disassembled and transported if necessary. This would be a dream structure for places like Minnesota, Canada, Alaska, Siberia and Mongolia because it would be super comfortable, inexpensive, portable, wind resistant, owner built and could be built in many sizes. Add a skylight, rocket stove, small solar panel and composting toilet and then you can laugh at the wind howling by.

Note: you can use recycled bags if available (often farmers have them). You can also order tubes from poly bag suppliers. They make custom sizes. Tubes are faster to fill since you don’t have to stop and tie the ends as often. A 12″ tube (measured when empty) that provides 10″ of insulation when filled would be ideal for many cold climates. Simply tie the tubes to the yurt frame with twine. Use whatever insulation is most practical in your area.

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One possible use of earthbags I haven’t seen so far is using bags of vermiculite, perlite, scoria or pumice for insulating yurts, tents and other dwellings.  Kelly Hart used scoria-filled bags on his domes, and we’ve discussed ceiling insulation previously, but I’m talking about stacking (free standing) bags inside of a structure for wall insulation.

Rice hulls could be used as fill material, but they’re not as ideal as the other options above.  For instance, rodents could chew through a bag searching for small pieces of rice.  Straw bales could be used, but they are somewhat vulnerable to fire and water damage when left exposed.  Plastering the walls would prevent these problems, but I’m exploring ways to stack bags of insulation without having to plaster.

Not having to plaster the walls would save lots of time and effort.  This would be ideal for a temporary structure – for example, living in a yurt through winter while the main house is being built, or living in a tent in a desert.  This system would make it easy to pack things up and move with a minimum of effort.  And, the insulation could be reused elsewhere – possibly in your permanent home.

Note: Bags of insulation do take up quite a bit of space, however, in a very cold or hot climate this plan may be beneficial.

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Most earth structures such as adobe are located in hot, dry climates. But what if you live in a cold climate and want the benefits of low-cost earth building techniques? Earthbag building has the unique advantage of providing either thermal mass or insulation, and therefore can be adapted for cold climates with an insulated fill material. Scoria, pumice, perlite, vermiculite or rice hulls could all be used for insulation.

One possibility is to add a seam lengthwise down earthbags or polypropylene tubes to divide them into two compartments. The outer part could be filled with insulation; the inner part with soil. This would create an insulated wall with thermal mass on the interior. For many situations, this is an ideal wall system.


The placement of the seam could vary, depending on the climate. In a mild climate like New Mexico, I would add about 4”-5” of insulation on the outside. This would provide about R-10 insulation. In a slightly colder climate the seam could go down the middle (50% insulation/50% soil).  In extremely cold or extremely hot climates I would fill the bags with 100% insulation (or all earth in a hot climate if insulation wasn’t available).

To read the entire article, go to SearchWarp.com.

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Earthbag building (also called sandbag building) is surely one of the lowest cost, most practical building methods. First used by the military for building durable, bullet and blast resistant structures, this building method has recently experienced a surge of interest among do-it-yourself builders. There are now an estimated 1,000 to 1,500 earthbag structures, including homes, offices, shops, schools, temples, clinics, orphanages and even ecovillages.

One of the strongest selling points is affordability. A simple earthbag dome, for example, using recycled grain bags and earth can be built for around $100. A larger, more comfortable home can be built for around $500-$1000. The EarthDome House at Terrasante Village in Tucson, Arizona is just one example.

To read the entire article, go to EzineArticles.

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Kelly and Rosana Hart's earthbag home in Crestone, Colorado.

Kelly and Rosana Hart's earthbag home in Crestone, Colorado.

In my opinion nothing beats the warmth and rustic beauty of natural materials. Many people choose natural building materials to save money, and that makes perfect sense. But let’s not overlook design aesthetics. A home is much more than just an assemblage of materials. Natural materials have a way of seamlessly blending everything together, turning a house into an inviting home.

Kelly and Rosana Hart’s earthbag house is one example of this. Made almost entirely of locally obtained, natural materials such as earthbags filled with crushed volcanic rock (for maximum insulation), earth floors, stone and recycled materials, this home has become the quintessential natural home, having been featured in at least 10 books and magazines.

To read the rest of the article, please go to Eco-Ezine.

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